Adding your event hashtag is quick and easy! A hashtag, written with a # symbol, is used to index keywords or topics on Twitter and allows people to easily follow topics they are interested in. (Source:Twitter Support).
First, double check to ensure that Enable Twitter Integration is selected in your settings. (Edit Event > Twitter)
Next, enter the event hashtag in the Event Hashtag field:
Then, click the green [Save] button on the grey primary navigation bar.